[SCSI] tgt: use scsi_init_io instead of scsi_alloc_sgtable

If we export scsi_init_io()/scsi_release_buffers() instead of
scsi_{alloc,free}_sgtable() from scsi_lib than tgt code is much more
insulated from scsi_lib changes. As a bonus it will also gain bidi
capability when it comes.

[jejb: rebase on to sg_table and fix up rejections]

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 14 insertions, 34 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 7c4c889c5221..69fd62183bab 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -746,7 +746,7 @@ static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
         return mempool_alloc(sgp->pool, gfp_mask);
 }
 
-int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+static int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
 {
         int ret;
 
@@ -762,15 +762,11 @@ int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
         return ret;
 }
 
-EXPORT_SYMBOL(scsi_alloc_sgtable);
-
-void scsi_free_sgtable(struct scsi_cmnd *cmd)
+static void scsi_free_sgtable(struct scsi_cmnd *cmd)
 {
         __sg_free_table(&cmd->sg_table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
 }
 
-EXPORT_SYMBOL(scsi_free_sgtable);
-
 /*
  * Function:    scsi_release_buffers()
  *
@@ -788,7 +784,7 @@ EXPORT_SYMBOL(scsi_free_sgtable);
  *              the scatter-gather table, and potentially any bounce
  *              buffers.
  */
-static void scsi_release_buffers(struct scsi_cmnd *cmd)
+void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
         if (cmd->use_sg)
                 scsi_free_sgtable(cmd);
@@ -800,6 +796,7 @@ static void scsi_release_buffers(struct scsi_cmnd *cmd)
         cmd->request_buffer = NULL;
         cmd->request_bufflen = 0;
 }
+EXPORT_SYMBOL(scsi_release_buffers);
 
 /*
  * Function:    scsi_io_completion()
@@ -1001,7 +998,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
  * Returns:     0 on success
  *              BLKPREP_DEFER if the failure is retryable
  */
-static int scsi_init_io(struct scsi_cmnd *cmd)
+int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
 {
         struct request     *req = cmd->request;
         int                count;
@@ -1016,7 +1013,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
         /*
          * If sg table allocation fails, requeue request later.
          */
-        if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {
+        if (unlikely(scsi_alloc_sgtable(cmd, gfp_mask))) {
                 scsi_unprep_request(req);
                 return BLKPREP_DEFER;
         }
@@ -1036,6 +1033,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
         cmd->use_sg = count;
         return BLKPREP_OK;
 }
+EXPORT_SYMBOL(scsi_init_io);
 
 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
                 struct request *req)
@@ -1081,7 +1079,7 @@ int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 
                 BUG_ON(!req->nr_phys_segments);
 
-                ret = scsi_init_io(cmd);
+                ret = scsi_init_io(cmd, GFP_ATOMIC);
                 if (unlikely(ret))
                         return ret;
         } else {
@@ -1132,7 +1130,7 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
         if (unlikely(!cmd))
                 return BLKPREP_DEFER;
 
-        return scsi_init_io(cmd);
+        return scsi_init_io(cmd, GFP_ATOMIC);
 }
 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
 
diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index 01e03f3f6ffa..91630baea532 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -331,8 +331,7 @@ static void scsi_tgt_cmd_done(struct scsi_cmnd *cmd)
 
         scsi_tgt_uspace_send_status(cmd, tcmd->itn_id, tcmd->tag);
 
-        if (scsi_sglist(cmd))
-                scsi_free_sgtable(cmd);
+        scsi_release_buffers(cmd);
 
         queue_work(scsi_tgtd, &tcmd->work);
 }
@@ -353,25 +352,6 @@ static int scsi_tgt_transfer_response(struct scsi_cmnd *cmd)
         return 0;
 }
 
-static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
-{
-        struct request *rq = cmd->request;
-        int count;
-
-        cmd->use_sg = rq->nr_phys_segments;
-        if (scsi_alloc_sgtable(cmd, gfp_mask))
-                return -ENOMEM;
-
-        cmd->request_bufflen = rq->data_len;
-
-        dprintk("cmd %p cnt %d %lu\n", cmd, scsi_sg_count(cmd),
-                rq_data_dir(rq));
-        count = blk_rq_map_sg(rq->q, rq, scsi_sglist(cmd));
-        BUG_ON(count > cmd->use_sg);
-        cmd->use_sg = count;
-        return 0;
-}
-
 /* TODO: test this crap and replace bio_map_user with new interface maybe */
 static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
                                unsigned long uaddr, unsigned int len, int rw)
@@ -397,9 +377,11 @@ static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
         }
 
         tcmd->bio = rq->bio;
-        err = scsi_tgt_init_cmd(cmd, GFP_KERNEL);
-        if (err)
+        err = scsi_init_io(cmd, GFP_KERNEL);
+        if (err) {
+                scsi_release_buffers(cmd);
                 goto unmap_rq;
+        }
 
         return 0;